xfs_admin - change parameters of an XFS filesystem
xfs_admin [
-eflpu ] [
-O featurelist ] [
-c
0|
1 ] [
-L label ] [
-U uuid ] [
-r rtdev ]
device [
logdev ]
xfs_admin -V
xfs_admin uses the
xfs_db(8) command to modify various parameters
of a filesystem.
Devices that are mounted cannot be modified. Administrators must unmount
filesystems before
xfs_admin or
xfs_db(8) can convert
parameters. A number of parameters of a mounted filesystem can be examined and
modified using the
xfs_growfs(8) command.
The optional
logdev parameter specifies the device special file where the
filesystem's external log resides. This is required only for filesystems that
use an external log. See the
mkfs.xfs -l option, and refer to
xfs(5) for a detailed description of the XFS log.
- -e
- Enables unwritten extent support on a filesystem that does
not already have this enabled (for legacy filesystems, it can't be
disabled anymore at mkfs time).
- This option only applies to the deprecated V4 format.
- -f
- Specifies that the filesystem image to be processed is
stored in a regular file at device (see the mkfs.xfs -d
file option).
- -j
- Enables version 2 log format (journal format supporting
larger log buffers).
- This option only applies to the deprecated V4 format.
- -l
- Print the current filesystem label.
- -p
- Enable 32bit project identifier support (PROJID32BIT
feature).
- This option only applies to the deprecated V4 format.
- -u
- Print the current filesystem UUID (Universally Unique
IDentifier).
-
-c 0|1
- Enable (1) or disable (0) lazy-counters in the
filesystem.
- Lazy-counters may not be disabled on Version 5 superblock
filesystems (i.e. those with metadata CRCs enabled).
- In other words, this option only applies to the deprecated
V4 format.
- This operation may take quite a bit of time on large
filesystems as the entire filesystem needs to be scanned when this option
is changed.
- With lazy-counters enabled, the superblock is not modified
or logged on every change of the free-space and inode counters. Instead,
enough information is kept in other parts of the filesystem to be able to
maintain the counter values without needing to keep them in the
superblock. This gives significant improvements in performance on some
configurations and metadata intensive workloads.
-
-L label
- Set the filesystem label to label. XFS filesystem
labels can be at most 12 characters long; if label is longer than
12 characters, xfs_admin will truncate it and print a warning
message. The filesystem label can be cleared using the special
"-- " value for label.
-
-O
feature1=status,feature2=status...
- Add or remove features on an existing V5 filesystem. The
features should be specified as a comma-separated list. status
should be either 0 to disable the feature or 1 to enable the feature.
Note, however, that most features cannot be disabled.
-
NOTE: Administrators must ensure the filesystem is
clean by running xfs_repair -n to inspect the filesystem before
performing the upgrade. If corruption is found, recovery procedures (e.g.
reformat followed by restoration from backup; or running xfs_repair
without the -n) must be followed to clean the filesystem.
- Supported features are as follows:
- inobtcount
- Keep a count the number of blocks in each inode btree in
the AGI. This reduces mount time by speeding up metadata space reservation
calculations. The filesystem cannot be downgraded after this feature is
enabled. Once enabled, the filesystem will not be writable by older
kernels. This feature was added to Linux 5.10.
- bigtime
- Upgrade a filesystem to support larger timestamps up to the
year 2486. The filesystem cannot be downgraded after this feature is
enabled. Once enabled, the filesystem will not be mountable by older
kernels. This feature was added to Linux 5.10.
- nrext64
- Upgrade a filesystem to support large per-inode extent
counters. The maximum data fork extent count will be 2^48 - 1, while the
maximum attribute fork extent count will be 2^32 - 1. The filesystem
cannot be downgraded after this feature is enabled. Once enabled, the
filesystem will not be mountable by older kernels. This feature was added
to Linux 5.19.
-
-U uuid
- Set the UUID of the filesystem to uuid. A sample
UUID looks like this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16".
The uuid may also be nil, which will set the filesystem UUID
to the null UUID. The uuid may also be generate, which will
generate a new UUID for the filesystem. Note that on CRC-enabled
filesystems, this will set an incompatible flag such that older kernels
will not be able to mount the filesystem. To remove this incompatible
flag, use restore, which will restore the original UUID and remove
the incompatible feature flag as needed.
-
-r rtdev
- Specifies the device special file where the filesystem's
realtime section resides. Only for those filesystems which use a realtime
section.
- -V
- Prints the version number and exits.
The
mount(8) manual entry describes how to mount a filesystem using its
label or UUID, rather than its block special device name.
mkfs.xfs(8),
mount(8),
xfs_db(8),
xfs_growfs(8),
xfs_repair(8),
xfs(5).